It was a crime that left Australians horrified. Eleven-year-old Luke Batty, brutally killed by his father during a mid-week cricket practice, his mother Rosie and others nearby.

"For some reason I thought he was safer in an open space with people around and then you realise that you're not safe." Rosie Batty, Luke's Mother

Within hours, Luke's father Greg Anderson was also dead - shot in the chest at the scene when he threatened police.

This week on Four Corners, Geoff Thompson reports on the often hidden scourge of family violence that was laid bare in a very public way in an outer Melbourne suburb earlier this year.

For years, Rosie Batty struggled to manage the increasingly violent behaviour of the father of her son. She called for help - loud and clear. She involved the police, the courts, child protection and social workers to keep her son and herself safe. But this didn't happen.

"His behaviour was never going to… put him away, but you can't help but think that some intervention may have been just enough for him to rethink, or maybe enough of a red flag for me to understand what acute danger Luke and I were in." Rosie Batty

Did these agencies do enough to help Rosie and Luke? Could Luke's brutal death have been prevented?

"...when you need to look someone in the eye like Rosie and hear how the system dealt with her and understand how the system may have let some of those people down, it's very, very confronting." Ken Lay, Victorian Police Commissioner

Rosie's Story, reported by Geoff Thompson and presented by Kerry O'Brien, goes to air on Monday 14th July at 8.30 pm on ABC 1. It is replayed on Tuesday 15th July at 11.00 am and 11.30 pm. It can also be seen on ABC News24 on Saturday 19th July, ABC iview and at abc.net.au/4corners.